|If krill oil is not fish oil 2.0 what is it good or even bad for, then?|
As I previously mentioned, the low rate of incorporation of triglyceride-bound omega-3 fatty acids into the tissue of the Male C57BL/6J mice, which were kept on a high fat diet that contained 24% (wt/wt) fat (21.3% lard and 2.3% soy oil), or, alternatively, the same HF diet supplemented with FO (15.7% lard, 2.3% soy oil and 5.8% FO) or KO (15.6% lard, 2.3% soy oil and 5.7% KO) for 6 weeks, is eventually not surprising.
Eventually, you can think of the difference between phospholipid bound (P) and triglyceride bound (T) fatty acids with respect to their chances of being incorporated into your cells as bricks (P) and menirs (T). Obviously, the former can be used right away, to build a new home. The latter, on the other hand, have to be processed, before they can become part of a building - or, if we leave our analogy, your cells. If you have enough "stones" aka omega-3s - and the 5.8% fish oil in the diet obviously were more than enough - you will still end up at similar serum levels (obviously it's not exactly feasible to consume ~6% of your diet, i.e. at least 120kcal = 13g of fish oil, everyday; therefore bioavailability still is a clear advantage for krill oil).
|Popping more than 10g+ of fish oil a day is madness. Making the right fish choices and eating those fish twice a week, on the other hand, is smart!|
In conjunction with its effects on the expression of genes involved in the early steps of isoprenoid/cholesterol and lipid synthesis, the ability to "clear" the pro-inflammatory arachidonic acid from your blood makes krill oil the perfect choice for people who suffer from chronic inflammation.
For fish oil, things look (not generally but) slightly different. While fish oil will also have an impact on arachidonic acid and cholesterol synthesis, the scientists found that its effects on the liver and the downstream effects on the levels of triglycerides, phospholipids and the very low density lipoprotein (VLDL) in the blood, as well as their accumulation in the liver is significantly more pronounced for fish vs. krill oil.
It's not all gold that glitters like fish oil, but "Krill Red" ain't necessarily better either
If you look at the data in Figure 1, you will also realize that fish oil had visibly (carnitine palmitoyl transferase 1 CPT1, ACOX), but not significantly more potent effects on the activity of fat burning enzymes in the liver. In view of the fact that the net results in form of body weight gain where identical, it's yet not just statistically, but probably also practically irrelevant.
Warning: Fish oil can clog your liver, as well and the increase in fatty acid synthesis in the liver (FAS) you see in Figure 1 could actually explain the observations I report in "Too Much of a Good(?) Thing: When Fish Oil Starts Clogging Your Arteries and Fattening Up Your Liver." | read more.Although, if you think of a high triglyceride scenario, the use of fish oil appears to be a better choice to reduce the amount of the "carbohydrates" among the fatty acids (trigs will usually rise in response to problems w/ glucose metabolism and drop rock bottom in most people who stop eating carbs).
|Figure 1: Rel. changes (% of HF diet) in liver fatty acid metabolism (left) and body weight development (right) of the mice over the study period (calculated base on Tillander. 2014)|
- Tillander et al. "Fish oil and krill oil supplementations differentially regulate lipid catabolic and synthetic pathways in mice". Nutrition & Metabolism 2014, 11:20 doi:10.1186/1743-7075-11-20
- Yamada, Hidetoshi, et al. "Hydroxyeicosapentaenoic acids from the Pacific krill show high ligand activities for PPARs." Journal of lipid research 55.5 (2014): 895-904.